feat: add filter support for DOK awards

The DOK award type (used for DLD award) now supports filtering by band,
mode, and other QSO fields. This allows creating award variants like:
- DLD on specific bands (80m, 40m, etc.)
- DLD on specific modes (CW, SSB, etc.)
- DLD with combined filters (e.g., 80m + CW)

Changes:
- Modified calculateDOKAwardProgress() to apply filters before processing
- Added example awards: dld-80m, dld-40m, dld-cw, dld-80m-cw
- Filter system uses existing applyFilters() function

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/backend/services/awards.service.js

@@ -27,6 +27,10 @@ function loadAwardDefinitions() {
       'sat-rs44.json',
       'special-stations.json',
       'dld.json',
+      'dld-80m.json',
+      'dld-40m.json',
+      'dld-cw.json',
+      'dld-80m-cw.json',
     ];
 
     for (const file of files) {
@@ -173,9 +177,9 @@ export async function calculateAwardProgress(userId, award, options = {}) {
 async function calculateDOKAwardProgress(userId, award, options = {}) {
   const { includeDetails = false } = options;
   const { rules } = award;
-  const { target, displayField } = rules;
+  const { target, displayField, filters } = rules;
 
-  logger.debug('Calculating DOK-based award progress', { userId, awardId: award.id, target });
+  logger.debug('Calculating DOK-based award progress', { userId, awardId: award.id, target, hasFilters: !!filters });
 
   // Get all QSOs for user
   const allQSOs = await db
@@ -185,10 +189,17 @@ async function calculateDOKAwardProgress(userId, award, options = {}) {
 
   logger.debug('Total QSOs for user', { count: allQSOs.length });
 
+  // Apply filters if defined
+  let filteredQSOs = allQSOs;
+  if (filters) {
+    filteredQSOs = applyFilters(allQSOs, filters);
+    logger.debug('QSOs after DOK award filters', { count: filteredQSOs.length });
+  }
+
   // Track unique (DOK, band, mode) combinations
   const dokCombinations = new Map(); // Key: "DOK/band/mode" -> detail object
 
-  for (const qso of allQSOs) {
+  for (const qso of filteredQSOs) {
     const dok = qso.darcDok;
     if (!dok) continue; // Skip QSOs without DOK